This invention relates to an apparatus for discharging weighed articles in a combinatorial weighing-type automatic weighing system, and to a method of discharging the articles.
An automatic weighing system now in practical use operates by supplying articles to a plurality of weighing machines, computing combinations of weight values obtained from the weighing machines, selecting a combination of the weight values the sum total whereof is equal to a predetermined target weight or closest to the target weight, and discharging only the articles contained in the weighing machines corresponding to the selected combination (referred to as the "optimum combination"), whereby there is obtained a batch of the articles the weight whereof is equal or closest to the target weight.
The automatic weighing system of the type described is equipped with a collecting chute underlying the weighing machines for collecting the articles discharged from the weighing machines corresponding to the optimum combination, and is arranged so that the articles which have been weighed out are supplied from the collecting chute to a packaging apparatus used in conjunction with the weighing system. With such an arrangement, it is required that the automatic weighing system be operated in coordination with the packaging apparatus. More specifically, the interval between weighing cycles performed by the automatic weighing system must be controlled in such a manner that the articles are discharged from the collecting chute in conformance with the packaging apparatus' processing time.
When the weighing operation of the automatic weighing system is speeded up to accommodate an increase in the processing capability of the packaging apparatus, the interval between discharge cycles for the discharge of articles from the weighing machines into the collecting chute is shortened. This means that when one batch of the articles has been discharged into the collecting chute, the next batch will follow shortly thereafter, so that the discharged article batches mix within the chute or, worse, enter the chute in continuous fashion, making it difficult or impossible for the packaging apparatus supplied with the articles to package them into discrete quantities. This places a limitation on the extent to which the processing capability of the overall system can be improved.
An alternative arrangement aimed at solving this problem is to steepen the incline of the collecting chute walls along which the articles slide in order to hasten the rate at which the articles pass through the chute. The inevitable result of this expedient, however, is to enlarge the vertical dimension of the collecting chute and, hence, the overall height of the weighing system.
Another proposal is to provide the weighing hopper of each weighing machine with first and second gates, and provide the collecting chute with a first collecting route for receiving the articles discharged from each weighing hopper when its first gate is opened, and a second collecting route for receiving articles discharged from each weighing hopper when its second gate is opened, with the articles being introduced into the two routes in alternating fashion. This permits the article batches to be supplied to the packaging apparatus intermittently without the mixing of successively discharged batches. However, even with this arrangement, the articles scatter while sliding down along the interior of the collecting chute, so that a certain amount of time is required from the beginning to the end of the discharge in each collecting route. Hence, there is the danger that the article batches in the two routes will mix at the point where they connect with the packaging apparatus. As a result, the time interval between discharges from the weighing machines to the collecting chute cannot be shortened sufficiently. In such case, a packaging apparatus may be provided for each of the two collecting routes, or a single packaging apparatus having dual packaging functions, one for each collecting route, may be provided. However, either expedient raises equipment costs by a wide margin.